1. Field of the Invention
This invention relates generally to systems and method for reading data from and writing data to data storage medium by employing the optical recording technology. More particularly, this invention is related to an improved optical data access system. The data access system is implemented in a portable data card drive device and in a high speed subsystem for reading data from and writing data to An optical data card which has a novel data track configuration for storing data with uniform density. Data can be stored for user applications or related to application system configurations.
2. Description of the Prior Art
Conventional technology of reading-writing data on concentric circular data tracks often presents a problem that the data-bit density varies between the outer tracks and the inner tracks. The variable bit density in data storage is due to a geometrical factor that the outer data tracks are much longer in length than the inner tracks. A common practice is to form the inner tracks with a capacity to store the data bit at a higher bit density. A more complicate servo control system implemented with more complex signal-processing algorithms is required due to the variations of data storage density between different data tracks. Additionally, by varying the data storage density from the inner tracks toward the outside tracks, the data transfer rate is also changed in accessing data from the inner tracks then outside tracks. Such variation may also cause difficulties and complications in processing the data. Higher error rates may incur due to these variations between the inner tracks and the outer tracks.
Therefore, a need still exists for an improved data-card drive system to overcome the aforementioned difficulties encountered in the prior art. Specifically, this storage card drive system must provide a uniform density for data storage and a data-card drive system to access the data-storage card. Furthermore, it would be desirable that this system is portable and is also provided with several standardized sizes for processing standardized data-storage cards.